(demosponge) |
(flatworm) |
KINGDOM ANIMALIA
(=Metazoa)* (mainly from Ruppert & Barnes 2004 p. 220
|
(featherduster worm) |
(sea urchin) |
(octocoral) |
(gastropod) |
Modified from
Tree of Life (after Ruppert & Barnes 2004 p. 220; Brusca & Brusca 2003 p. 875) |
(crab) |
(sea squirts) |
=========================================== Porifera (sponges) | | ======================================== Placozoa (placozoans, Trichoplax) | | | | ==================================== Cnidaria (jellyfish, anemones, corals, etc.) | | | <<=M=| | | |(branch uncertain)============== Ctenophora (comb-jellies) | | | | | | | | ========================= Platyhelminthes (flatworms, tapeworms, etc.) | | | | | Mo=| | | | (branch uncertain)=X= 'pseudocoelomates' (nematodes, rotifers, etc.) | | | | | | | | =P*=| | ================= Nemertea (ribbon worms) | | | | | | | =E==| | | =A==| | ======== Mollusca (snails, clams, squids, etc.) | | | | | ======| | | | =C*=| | ======== Sipuncula(peanut worms) | | | | | | | | | | ===== Annelida (segmented worms) | | | ===| ===| | | | | ===| ===== Pogonophora (beard worms, vent worms; now put in the Annelida) ===| | | | | | | ===| ======== Echiura (proboscis worms) | | | | | | ======= Onychophora (velvet worms) | | | | | | =XR=| ==== Tardigrada (water bears) | | ===| =B*=| ==== Arthropoda (insects, spiders, crabs, etc.) | | |(branch uncertain)== Chaetognatha (arrow worms) | | | |(branch uncertain)== lophophorates (bryozoans, brachiopods, etc.) | | ===DA===| ============== Xenturbellida (Xenoturbella) | | | =Am=| ========== Echinodermata(starfish, urchins, etc.) | | ====| | | ========== Hemichordata (acorn worms, pterobranchs) ===| ================== Chordata (sea squirts, vertebrates, etc.)
b) sessile adult, superficial radial symmetry** c) monociliated cells** d) radial, indeterminate cleavage e) blastula stage embryo f) diplosome** g) type IV collagen Mo: motile adults; dorso-ventral body axis b) diploblastic organization c) true radial symmetry d) gastrula stage embryo e) blind gut (no anus) f) true gonads g) true nervous system with synapses h) striated muscle b) cephalization c) triploblastic organization (extensive mesoderm) d) organ-system level of organization e) protonephridia A: anus present (i.e., complete gut) |
b) mesoderm from single (mesentoblast) cell c) mesoderm develops from mesenchyme cells c) fate of first germ cell set at 5th cleavage d) mouth (and sometimes anus) from blastopore e) multiciliated cells b) trochophore-like larva with apical cilia c) larvae swim with compound cilia X: exoskeleton that must be molted R= PANARTHOPODA b) mesoderm from epithelial cells c) coelom via enterocoely d) blastopore yields anus e) tripartite coelom and body plan f) monociliated cells** (some multiciliated) Am= Ambulacraria |
The phylogenetic trees for animal phyla presented here represent a very classical view of animal relationships. Recent molecular data are raising questions about many of these relationships, particularly among the bilaterian taxa. For an alternative view and discussion see the Metazoa systematics page of the University of California Museum of Paleontology.
Important differences include:
- Wolf, Y. I. et al. (2004). Coelomata and not Ecdysozoa: Evidence from genome-wide phylogenetic analysis. Genome Research 14(1): 29-36.
- Hughes, A. L. and R. Friedman (2004). Shedding genomic ballast: Extensive parallel loss of ancestral gene families in animals. Journal of Molecular Evolution 59: 827-833.
For another detailed consideration of phylogenetic relations that includes fossil taxa and references to the original literature, see Mikko's Phylogeny Archive.
Some recent, accessible papers on molecular phylogenies for animal phyla include: